Currently, an auto negotiation process of a physical downlink shared channel (Physical Downlink Shared Channel, PDSCH) in a Long Term Evolution (Long Term Evolution, LTE) system is: A user equipment (User Equipment, UE) estimates channel information that is used to measure channel state information (Channel State Information, CSI); by using the estimated channel information, the UE calculates a signal to interference plus noise ratio (Signal to Interference plus Noise Ratio, SINR) based on an optimal rank indication (Rank Indication, RI) and/or a precoding matrix indication (Precoding Matrix Indication, PMI); the UE quantizes the calculated SINR into a 4-bit channel quality indicator (Channel Quality Indicator, CQI); the UE reports the CQI value to an evolved NodeB (evolution NodeB, eNB); the eNB allocates a modulation and coding scheme (Modulation and Coding Scheme, MCS) to the UE according to the CQI value reported by the UE and network conditions, where the MCS is used to indicate the modulation and coding scheme currently used by the PDSCH; and the UE receives PDSCH data according to the MCS. In the process of quantizing the SINR into the CQI, a main interval of the SINR is (−7 dB, 19.488 dB), and SINRs outside the interval are processed in a saturation manner.
In a hotspot scenario such as a relay (Relay) or LTE hotspot improvements (LTE Hotspot Improvements, LTE-Hi) scenario, all SINR values obtained by the UE are large. For example, under certain conditions, almost 50% of SINR values of the UE are greater than 20 dB. However, because the SINR values greater than a maximum value of the main interval are processed in a saturation manner in the process of quantizing the SINR into the CQI, and an index of a CQI corresponding to an SINR in the saturation manner is 15, the UE at most can select only a modulation and coding scheme corresponding to the CQI whose index is 15, which restricts a terminal from selecting a higher modulation and coding scheme and affects system performance.